Up to the present time, the decorating or marking of plastic bottles has mostly be done in only one color. Serigraphy has been found to be an appropriate and economical solution for this type of printing since it gives a clear printing with a contrasting effect, and since it has proven to be resistant to the products contained in the bottles as well as to wear due to friction during transport, and this with low-cost printing equipment which is easily adaptable to any type of surface and requires little if any training on the part of the operators.
However, these types of bottles having become more than containers, but also trademarks, symbols, or even means for commercial advertizing, it has now become necessary to print them in more than one color for composing ever more complex designs. The machines have therefore had to be specialized, for producing a predetermined decoration on a special design of bottle, in order to meet these demands. This has obliged printers to acquire machines of different types for printing different types of bottles, which has meant high investment costs that often are not recovered due to the instability of the market. In any case, no printing method, serigraphy included, has offered a satisfactory solution to the problem arising from those printing demands. There only remains the use of labels, decalcomania, or transfers under heat, all of which have proven to be rather expensive due to their developing process, their application to the bottle, their lack of versatility in adapting to different types of bottles and the difficulty in obtaining a good resistance to the contents of the bottle.